This invention relates to an apparatus for furrow opening. More specifically, it is a soil opening apparatus used with tillage and planting machinery.
No-tillage is a planting system whereby a crop is planted directly into an essentially unprepared seedbed. It means the elimination of any tillage operations from the previous crop through harvest other than what is necessary to properly place and cover the seed.
There are three main areas in a no-tillage planting system which require adequate management, materials and equipment; namely, development and utilization of a surface mulch, application of herbicides and insecticides without tillage and planting (or transplanting) with minimum mulch disturbance. The mulch is used for moisture conservation and to protect the field surface from wind and water erosion. The herbicides and insecticides establish a seedbed free from competition by killing the cover crop to convert it into a mulch and by controlling weed growth and insect pests. The planter cuts through the mulch to open a furrow in the soil sufficient to deposite seed (or plants) and closes the furrow.
Special machine requirements must be met. No-tillage planters must be designed to be flexible enough to tranverse moderate undulations without effecting the planting depth on any row and to have components which will track around contour curves. In areas where the benefits from the control of wind and water erosion control are the greatest, no-tillage planters and transplanters will need to operate through wide ranges of soil hardness and moisture conditions in the same field. Although no-tillage planting in mulches gives better yield responses in crusting, non-fracturing soils, the practice has already spread to other soil types. Basic requirements of a no-tillage planter opening unit are that it floats over subsurface obstructions and plants at the desired depth across a field moist enough for seed germination but dry enough for tractor mobility.
The instant novel soil furrow opener, which we term the "combination-opener," consists of a smooth rolling coulter operating deeper than the desired furrow depth and a pair of discs mounted at appropriate angles (5.degree. at 45.degree. from horizontal) so that they contact the rolling coulter at or slightly below the soil surface and so that they open a furrow the minimum desirable width for deposition of transplants or of seed.
Soil penetration with the combination opener is achieved by applying vertical force downward either by direct weighting with ballast or by weight transfer through a device such as springs from the weighted machine frame. The prototype transplanter uses direct ballast weights on the opener frame. Direct ballast applies best to one-row machines. The prototype planter is a demonstration of the use of weight-transfer springs. Weight-transfer methods allow flotation of each row unit of a multiple-row machine while maintaining adequate downward force and while furrow depth is maintained by devices such as depth bands (as used on the prototype planter) or by gauge wheels. Vertical penetration force varies considerably with field conditions. We suggest using 600 pounds per row unit to facilitate operation in the hardest soil condition that we have encountered. The weight of riding operators on transplanters is considered as part of the 600 pounds but planting units will require the total in ballast excluding seed and fertilizer weight.
Furrow depth is controlled by using gauge wheels on the supporting tool bar for the one-row prototye transplanter. This would possibly be adequate also for two-row machines. Seed planting depths may require closer control than transplanting depths and planters are normally used in four-row or larger combinations. For these reasons, each planter row unit must be individually suspended so that it can follow terrain undulations by using either depth bands (from conventional double-disc opener planters) on each disc or by using gauge wheels mounted on one or both sides of each unit.
No-tillage transplanters using double-disc openers or combination-openers require a pair of narrow wingsmounted behind the discs and operating below the soil surface to hold the furrow open for transplant deposition.
Seed planters deposit seed between the discs of the combination-opener with the seed tube placed forward so that the discs do not move soil into the end of the tube and so that the seed falls where the furrow is opened the widest. A seed firming wheel is spring-loaded and mounted to track behind the seed tube and between the trailing portion of the two discs. Because of the narrowness of the furrow and because of its natural tendency to close after passage of the two discs, the seed firming wheel is also narrow. It consists of a disc 1/4 to 3/4 in. thick and 9 in. in diameter mounted similar to conventional 1-in. by 10-in. rubber seed firming wheels.
Furrow closure under no-tillage field conditions has been a constant problem with conventional no-tillage planters. The problem appears to be associated with generally uncontrolled tracking between cutting coulters, furrow openers and rear press wheels. The combinationopener design provides cutting and furrow opening functions without tracking problems and with a minimum of soil disturbance. The resulting furrow is a cleanly cut slit in the soil and surface trash. Closure of this furrow requires the application of pressure upon the upraised soil directly adjacent to the open slit. This must be performed on both sides of the furrow. We have found that a pair of narrow weighted press wheels with their axles set at 20.degree. (transplanter) or 10.degree. to 15.degree. (planter) from horizontal, so that they are closest together at bottom-dead-center, conform to the natural shape of the furrow edge and effectively close the furrow as they closely trail the combination opener. This wheel system is used for our transplanter and planter prototypes. The edges of the wheels are 1/2 in. wide and taper to 11/2 in. wide. They also provide traction for driving the transplating plantchain and seed hopper mechanisms, respectively. The transplanter press wheels are 22 in. in diameter and weigh 100 lb. each. They effectively close furrows which are nominally 3.5 in. deep. The planter press wheels are 14 in. in diameter and weigh 70 lb. each. They effectively close furrows which are 1 in. to 2 in. deep, depending upon the crop. The press wheels on both machines are hinged to allow flotation over undulated terrain independent of vertical movement of the combination-opener frame. This hinging allows constant furrow-closing pressure independent of the penetration force required for the combination-opener.
Components in row units must track one another if their functions are to be properly executed. Tracking becomes especially critical when multiple row units are combined, when transplanting or planting is to be done on curved or contoured rows, and when operating on side slopes. The combination-opener and press wheels can be pivot-mounted so that they track almost perfectly. The combination-opener frame is pivotmounted from the tool bar on a vertical post similar to the mounting of a rolling coulter on a moldboard plow. This allows the combination opener to pivot in response to changes in direction of travel. The vertical post is positioned ahead of the rolling coulter and discs so that they tend to run on a straight line or smooth curve rather than leading off to one side or the other.
The rear press wheels must also track. This is extremely important in the case of the transplanter because non-tracking would damage the transplants in the row. A second pivot point with a vertical post is provided for the rear press wheels. In the case of the transplanter, it is mounted on a special frame attached to the tool bar to avoid blocking the open-center frame which is the path for the transplants. Extensions of the combination-opener frame guide the rear press wheel frame, at a point described by the intersection of tangents to their turning arcs so that near-perfect tracking is achieved. Other designs may give the same performance. In the case of the planter, the vertical pivot post is mounted on the rear of the combinationopener frame and guidance is not required. Both machines track at the selected minimum turning radius of 50 ft. and on side slopes.